Bosco L, Filoni S, Cannata S
J Exp Zool. 1979 Aug;209(2):261-82. doi: 10.1002/jez.1402090208.
Larval Xenopus laevis at stage 56 (Nieuwkoop and Faber, '56) were subjected to various types of lentectomy: (1) simple lentectomy, from the pupillary space after incision of outer and inner cornea; (2) lentectomy from the dorsal region of the eye; (3) lentectomy from the dorsal region of the eye and simultaneous incision of the outer cornea; (4) lentectomy from the dorsal region of the eye and simultaneous incision of the outer and inner cornea. The results obtained show that the outer cornea underwent lens-forming transformations only when the inner cornea had been incised, thus permitting outer cornea (Experiments I-IV). No lens regeneration occurred when the inner cornea was left intact (Experiments II, III). It was concluded that the factor(s) allowing the lens-forming transformations of the outer cornea is not an aspecific nutritional factor(s) but a more specific factor(s) that cannot reach the outer cornea when the inner cornea is intact. Therefore, the absence of the lens and sufficient nutrient available to the outer cornea are not enough to allow lens regeneration from the outer cornea. When lens removal was carried out through the dorsal part of the eye (Experiments III-IV) the lens regenerated from the pericorneal epidermis of this region in a large number of cases.
处于第56阶段（Nieuwkoop和Faber，1956年）的非洲爪蟾幼体接受了各种类型的晶状体切除术：（1）简单晶状体切除术，在切开外层和内层角膜后从瞳孔空间进行；（2）从眼睛的背侧区域进行晶状体切除术；（3）从眼睛的背侧区域进行晶状体切除术并同时切开外层角膜；（4）从眼睛的背侧区域进行晶状体切除术并同时切开外层和内层角膜。所获得的结果表明，只有当内层角膜被切开从而使外层角膜能够进行时，外层角膜才会经历晶状体形成转化（实验I-IV）。当内层角膜保持完整时，没有发生晶状体再生（实验II、III）。得出的结论是，允许外层角膜进行晶状体形成转化的因素不是一种非特异性营养因素，而是一种更特异性的因素，当内层角膜完整时该因素无法到达外层角膜。因此，晶状体的缺失以及外层角膜可获得足够的营养并不足以使外层角膜再生晶状体。当通过眼睛的背侧部分进行晶状体摘除时（实验III-IV），在大量情况下晶状体从该区域的角膜周表皮再生。
